1. Field of the Disclosure
The present disclosure relates to a torque index sensor.
2. Discussion of the Related Art
Generally, almost every vehicle employs an electric power-assist steering system. The electric power-assist steering system generates an assist force based on the steering torque and the steering angle, so as to enhance the steering performance of the vehicle.
That is, a steering system that assists a steering force of a vehicle with a separate power is used to enhance the motion stability of a vehicle.
Conventionally, the auxiliary steering device uses hydraulic pressure, but an Electronic Power Steering (EPS) system adapted to transmit a rotation output of an electric motor to a steering shaft via a speed reduction mechanism has been increasingly employed these days from a viewpoint of a reduction in engine load, a reduction in weight, an enhanced steering stability and a quick restoring force.
The EPS system is such that an Electronic Control Unit (ECU) drives a motor in response to steering conditions detected by a speed sensor, a torque angle sensor and a torque index sensor to enhance a steering stability and provide a quick restoring force, whereby a driver can safely steer a vehicle.
Meantime, there is a need to measure a steering angular velocity, in addition to torque applied to a steering shaft and a steering angle, in order for the power device to be engaged to a force manipulating a steering wheel.
Generally, although an angle sensor is used in order to measure a rotation angle of the steering shaft, and a torque index sensor is used to measure a steering torque, a TAS (Torque Angle Sensor) is widely used recently that is capable of detecting a torque and a rotation angle in a single sensor.
However, the TAS capable of detecting the steering angle and the steering angular velocity is disadvantageous in that a manufacturing process is complicated, and failure and erroneous operations frequently occur, whereby TIS (Torque Index Sensor) of torque sensor method replaces the TAS.
A conventional configuration of TIS entitled as “torque sensor arrangement with rotational angle index detection” is disclosed in Korean Laid-Open Patent No.: 2011-0041468, where the sensor arrangement comprises a torque sensor for measuring a torque acting on a first shaft, wherein the sensor arrangement further comprises a rotational angle index unit that is adapted to detect and/or a defined rotational angle and/or a defined rotational angle range.
However, the torque sensor thus described is provided with a collector as a part for concentrating a magnetic flux of a magnet. The collector is secured at a housing, and if a coupling between the collector and the housing is loosened, a distance between the collector and the housing may become uneven to generate an error in a measured value of the sensor. Particularly, in case of a torque sensor applicable to an Electronic Power Steering (EPS) system that operates at a relatively higher temperature in the range of 80° C.˜120° C. than a room temperature, it is difficult to secure the collector using a double-sided tape or an adhesive.
It is, therefore, desirable to overcome the above problems and others by providing a collector fixing structure configured to guaranteeing reliability at a high temperature.